This invention relates to tire building and more particularly to a new and improved tire building drum that is collapsible for use in the forming of green tires.
In the building of green tires with multiple beads for heavy duty use such as by aircraft in high speed landings, it has become important to make a tire building drum that will facilitate the removal of the green tire from the tire building drum. Such tire drums have high crowns with deep undercut side flanges against which the multiple tire beads are positioned when the tire is being formed or built. These tires have relatively large cross-sectional areas and relatively small bead diameters. To improve the construction of these tires, the respective lateral side segments have been made removable to facilitate the collapse of the inner circumferential segments. More recently efforts had been made to retain the lateral side segments or end rings on the green tire while collapsing the plurality of drum segments (or inner circumferential segments). Thereafter with the inner drum segments collapsed the green tire and the end rings are removed from the drum. The end rings are then disassembled from the green tire. Note U.S. Pat. No. 3,366,526. The present invention is directed to a new and improved collapsible drum that in addition to facilitating the easy removal of a finished green tire also improves the side drum contour which permits less distortion of the green tire at the bead regions. This tire drum construction requires less movement of the ply stock and the rubber in the bead area during the curing process thereby substantially enhancing the quality of the tire being built since there is less movement of the materials. The drum includes end rings that are detachably removed from the drum and the green tire prior to collapse of the drum.